INSIDE NECK SCRATCHES - EFFECT

[searcher]

In other threads recently, a few folks have discussed concerns over inside neck scratches and galling due to turning necks, trimmer pilots, sizing buttons, etc.. Some folks say getting any level of galling or scratching inside the neck can be bad news. On the other hand, there is the IDOD trimmer which basically scratches the heck out of the entire inside of the neck by virtue of cutting it thinner. The makers of IDOD claim, and show in their online videos using their high-tech seating equipment, that the inside of the neck can be completely cut with circular scratches (for lack of a better definition) and, because they are all uniform, the end result for seating pressure uniformity is vastly improved over brass that is not inside turned. I tend to believe their seating claims and, knowing that, such "roughening" of the inside of the necks is not a concern relative to seating - so much. But - how about what these scratched cases impart on the bullet - and to what effect do those bullet scratches have on bullet performance downrange? I wonder this, as those IDOD cases are induced with a far rougher surface when inside turned that we would see resulting from scratches typical to dirty dies or a scratched expander ball. But what about the effect on the bullet which is seated in these "scratches". For those of you who have inside reamed your necks or used an IDOD, did you encounter degraded accuracy when using brass that was so prepared? The only thing right now from stopping me from purchasing an IDOD is wondering whether the potential harm to the bullet might be more significant as an accuracy detractor than the uniforming inside necks is a benefit. What do you say? Your input is appreciated.

 

[mgunderson]

There isn't a single answer to most questions like this. Try it and see if you can shoot the difference. You can take almost an issue in reloading and there will be many people successfully doing many different option. A universal absolute are rare in reloading. My opinion and others will disagree.

 

[Capt. Oblivious]

Ok here me out and I might be completely wrong but wont the rifling "marks" have a bigger impact on the bullet/bearing surface when it engages then said scratches?
After you shoot that piece of brass the scratches is going to be gone anyway, I think the base of the bullet has allot more to do with accuracy then marks on the bearing surface, again I could be completely wrong so lets see

 

[JSH]

I guess I don’t grasp all the galling and such on the inside of the case mouth. Seems a proper size mandrel with a good polishing would solve that problem?
Reaming cases, I thought that was a thing of the past, other than maybe with some really thick necks or bad donut issues. Center line of the case was my understanding?

Then there are those that want carbon on the inside of their necks for what ever reason, so the marred up finish would aid in keeping that on there to a point.

 

[AlNyhus]

I believe there is something there when it comes to inner neck finish. -Al

 

[stavey]

I had this experience when I tried the Henderson trimmer. Drove me crazy. I’m spending the time prepping brass to be perfect. Trying to shoot zeros. Why would I want galled necks ? I didn’t like the uneven chamfers it produced either. Sold the Henderson, went back to the giraud . Problem solved. In my opinion, if it can be avoided. Then avoid it.

 

[K22]

For many years I used a Lyman Case Trimmer which employs pilots to keep the case centered during trimming. Those pilots would "scratch", if that is the correct characterization, the inside of the necks, often in a non-uniform manner.

As a side note, further increasing the occurrence of this was in those days was I trimmed to SAMMI max case lengths which often resulted in a lot of trimming. A few years ago, I began measuring chamber length with a Sinclair chamber length gauge which reduced the amount of trimming needed to well over 50%.

About 20 years ago I switched to a Wilson Case Trimmer which employs case holders, not pilots, thus there is no contact with the inside of the neck during trimming.

Bottom line: I never detected any effect resulting from those "scratches" on the inside of the neck compared to cases trimmed with the Wilson trimmer (no scratches) as far as results on target.

 

[Tod Hendricks]

I hate scratching the inside of the necks! But does it matter, in my testing it didn’t.

First test you should do is to seat bullets and then pull them and visually inspect them, the cheapo digital microscope on my bench gets used quite often. I’ve recently started using the RCBS bullet puller, it’s much better than the Hornady, don’t care for the hammer types, just bought the PMA portable puller it appears to be very good.

Second test if you can, retrieve some of your bullets from the berm and see if any of those scratches are detectable. Being shot through a barrel is a pretty violent and disturbing event for those poor bullets.

 

[Eagle Six]

I think the difference it makes is in the amount of pressure and timing to release the bullet and get it going into the throat. If the inside neck is smooth and the bullet copper is smooth seems like it would make for a more consistent bullet release. Scratches/gulls that may be uneven may present an inconsistent release. I like consistency.

 

[JSH]

Does it matter, forget whom it was said something to the effect, “if you think it matters, then it probably does”. Subconscious is a strange thing, if it’s in your mind when your on the line, it does you no good.
Years ago when I shot a lot of IHMSA matches, buddy was running 6.5BR. His brass looked like it was found in the parking lot, just terrible stuff, yet he usually shot a 40x40 on a regular basis. I asked him if he ever cleaned his dies, a quick no was his answer.
Talked to him later on and he said he cleaned his dies and never realized how dirty they were.

Mandrels and decap rods that contact the neck, all get spun up and polished no matter who made them. A very small touch of lube doesn’t hurt a thing either. I have been using dry lube for a while now.

 

[marchboom]

The last thing (one of them anyway) I want is the case scratched...inside or out. If scratched necks were OK then the benchrest crowd would be using them. But they don't.

And if you use moly coated bullets the scratches would remove some of the moly.

 

[RegionRat]

I would suggest you make arrangements to have about 20 - 30 pieces of brass turned on the AUTODOD and test them against your alternatives.

 

[searcher]

Thanks for the feedback. Very interesting replies. Many years ago, I used to ream the insides of the necks to rid doughnuts. I couldn't really say how much effect the newly "roughened" neck interiors had relative to repeatable accuracy. I know getting rid of the doughnut helped - but I always wondered how much better the accuracy might have been if the doughnut had been removed AND the necks had been smooth as before. I'm guessing there are a lot of us "old timers" who have reamed necks - and many had far more experience doing so to see the effects on accuracy. Since the IDOD machine is not exactly inexpensive, I'm giving this a bit more thought than I do when plunking down a few bucks for a new "gadget", of which I have far too many that I ended up finding unnecessary.

 

[quest450]

I turn my BRA necks on AutoDOD and there's no rough surface or scratches inside or out, the manual version of the IDOD will leave rough surface and the upgrade to AutoDOD is worth the extra $$ IMO.
I don't clean my brass and I like carbon build up inside the necks for lubrication and consistent neck tension

 

[Lucky6547]

I’ve far more 17x, and 18x 199 and 200’s at 600 since I’ve started using the Henderson vs before using it…8-12x 197-200’s scores before using it…

 

[Webster]

In other threads recently, a few folks have discussed concerns over inside neck scratches and galling due to turning necks, trimmer pilots, sizing buttons, etc.. Some folks say getting any level of galling or scratching inside the neck can be bad news. On the other hand, there is the IDOD trimmer which basically scratches the heck out of the entire inside of the neck by virtue of cutting it thinner. The makers of IDOD claim, and show in their online videos using their high-tech seating equipment, that the inside of the neck can be completely cut with circular scratches (for lack of a better definition) and, because they are all uniform, the end result for seating pressure uniformity is vastly improved over brass that is not inside turned. I tend to believe their seating claims and, knowing that, such "roughening" of the inside of the necks is not a concern relative to seating - so much. But - how about what these scratched cases impart on the bullet - and to what effect do those bullet scratches have on bullet performance downrange? I wonder this, as those IDOD cases are induced with a far rougher surface when inside turned that we would see resulting from scratches typical to dirty dies or a scratched expander ball. But what about the effect on the bullet which is seated in these "scratches". For those of you who have inside reamed your necks or used an IDOD, did you encounter degraded accuracy when using brass that was so prepared? The only thing right now from stopping me from purchasing an IDOD is wondering whether the potential harm to the bullet might be more significant as an accuracy detractor than the uniforming inside necks is a benefit. What do you say? Your input is appreciated.

If I thought my necks were to rough on the i.d. I think I would take a wooden dowel, cut a notch in it put some 400 grit sandpaper in it so it's loose and flaps around. A couple seconds with an electric drill should help. I wouldn't try to make them perfectly smooth. I don't know why but in 50 years of reloading I never had any of the problems I hear about on this website. A light vis petroleum oil lube should be the best lube. It's been the best lube for fine machinery for over 100 years.

 

[searcher]

If I thought my necks were to rough on the i.d. I think I would take a wooden dowel, cut a notch in it put some 400 grit sandpaper in it so it's loose and flaps around. A couple seconds with an electric drill should help. I wouldn't try to make them perfectly smooth. I don't know why but in 50 years of reloading I never had any of the problems I hear about on this website. A light vis petroleum oil lube should be the best lube. It's been the best lube for fine machinery for over 100 years.

Yes - I can vaguely recall the old days when I never even though of things like this.....

 

[Bill K]

I would think the slight markings on the inside of the case mouth on the bullet would be of no bearing or something to fret about as the bullet is going to get more marks and damage from going down the bore, with it's land/grooves and other tool markings when fired and exiting the muzzle.

 

[dgeesaman]

What matters with scratches/markings/roughness in metal is the form of the the valleys in the roughness.

The IDOD tool and most any other spiral turning machine tool have a rounded nose, not a sharp point. So while it will leave a spiral surface finish, if you poke around with a magnifier or grind a cross-section, you will find pointy "A" at the peaks in the finish and rounded "U" lines in the valleys. As long as the valleys aren't "V"'s and the cut is clean, the strength remains quite good.

Direction of roughness matters too. Scratches along the length of the cartridge will tend to tear open with the expanding/contracting of the neck during firing. Scratches across the cartridge axis will tend to rupture if the expanding lengthwise is too severe.

FWIW.

 

[muleystalker]

I have heard some people saying they get scratches and galling on the Henderson trimmer and the giruard is superior. First off if you are galling or scraping necks with the Henderson it is user error. The OP asked if scratches or galling affects accuracy , IDK if the machine marks( I wouldn't call them scratches) that the IDOD leave in the case necks affect accuracy but if you watch a video done by F-Class John running the Henderson Trimmer along side his personal Giruard trimmer its very interesting, he then took the cases and seated bullets in them on the AMP press and the results were very interesting. The cases trimmed on the Giruard had a massive spike at the beginning and was somewhat rough and inconsistent while the cases trimmed on the Henderson were more consistent and a more even pressure throughout the seating cycle and did not have the big spike at the beginning. He then took the cartridges and shot them, the cartridges trimmed on the Henderson had smaller and more uniform groups than the groups shot with the Giruard trimmed brass. Also the SD's and ES'S with the Henderson trimmed casings were about half that of the Giruard cases across the board. I am not saying he is the authority on this but it seemed like a non biased comparison of the two units and some results on target that were derived from it. Its it a long and extensive study... no but it is still some valuable data in my book, not just hearsay on the internet. Here is the video, the seating test is about at the halfway mark.